The knowledge of dream or sleep can also awaken you to the truth

Patanjali Yoga Sutra Knowledge Sheet 38

There are only two states of consciousness. One is deep sleep or dreaming: day dream or night dream. Throughout the day one dreams, “Oh, what will happen to me? Or I will do this, I will do that.” Building castles in the air. However, once you know that you are day dreaming, that very moment a gush of energy overtakes you; you become alert and that alertness wakes you up to the reality. You are awakened. That awakening is prajna, samadhi. That moment alone you are fully alive and awakened to the truth of what is. Rest of the time, it is all sleep.

So, even knowing that, “Oh, I have been in deep sleep", "I have been in slumber", "I have been dreaming”, wakes you up. Patanjali has done a great favor to all by quoting this one sūtra: The knowledge of sleep awakens you.

When a person is sleeping, he is not aware that he is sleeping. The moment he realizes that he was sleeping or that this is sleep, he is already awake.

A person who is day dreaming does not know that he is day dreaming. The moment he knows that he was day dreaming, he wakes up to the reality that very moment, instantly. Even when you do (sudarshan) kriya and prānāyām and nothing is happening to you, are you not day dreaming or are you sleeping? There can only be two possibilities. There is no third possibility. Are you day dreaming? If you are day dreaming any amount of prānāyām cannot help you because your mind is galloping on a dream, “Oh I will be the President of Germany or some place”. You do not know how much of a headache it is to be the President of Germany. But the mind goes on such a race.

It is so difficult for politicians to get into any sādhana because their mind is in a constant state of daydreams. The pity is that they do not know that they are day dreaming and their dream is worth nothing. Worth nothing.